Microbial keratitis: a community eye health approach

Author(s): Keenan, Jeremy; Lietman, Thomas; O'Brien, KS; Lietman, TM; Keenan, JD; Whitcher, JP

Microbial keratitis is an infection of the cornea. Corneal opacities, which are frequently due to microbial keratitis, remain among the top five causes of blindness worldwide. Microbial keratitis disproportionately affects low-and middleincome countries. Studies indicate that the incidence of microbial keratitis may be up to 10 times higher in countries like Nepal and India compared to the United States.
Rural agricultural communities in lowand middle-income countries face a particularly high burden from corneal blindness. The most common cause of microbial keratitis is infection following a corneal abrasion. People are at greater risk of corneal injuries from agricultural activities, manual labour, and domestic work, which can result in infections of the cornea through contact with contaminated objects. Microbial keratitis tends to affect people at younger ages, in their prime working years, compared to other causes of blindness (such as cataract), which generally affect older people Rural communities in low-and middleincome countries face numerous obstacles in accessing appropriate treatment for microbial keratitis. Long delays in presen-tation and use of traditional medicines are common, increasing the risk of perforation and other complications that may result in vision loss. Patients with corneal ulcers may also face worse outcomes due to a lack of effective treatment options as well as an inability to afford medications when treatment is available. Opportunities for rehabilitation through surgical procedures are also limited by a lack of donor corneas for transplants.
Even when appropriate medical care is available, the corneal scarring that accompanies healing often results in visual impairment, despite successful antimicrobial treatment. Trials comparing antimicrobials for microbial keratitis generally have been unable to discern differences in visual acuity after treatment. An exception is that natamycin has been shown to be more effective than voriconazole for fungal corneal ulcers. Studies trialling adjunctive therapies with agents, such as topical corticosteroids, to reduce scarring, also have been largely unable to demonstrate major differences in visual outcomes in bacterial keratitis.
Given the limitations associated with available treatment options, secondary prevention (i.e. the prevention of visual impairment in someone with a corneal injury and/or infection) may be the best option for reducing vision loss associated with microbial keratitis.
A series of studies in Southeast Asia suggested that antimicrobial ointment applied soon after a corneal abrasion could dramatically reduce the incidence of microbial keratitis. The Bhaktapur Eye Study in Nepal was the first of these to show promising results for microbial keratitis prevention programmes at village level. In this study, primary eye care workers from the community were trained to diagnose corneal abrasions with fluorescein strips and a blue torch. They then provided topical chloramphenicol to all patients with a corneal epithelial defect. This study found that only 4% of patients treated for a corneal abrasion developed a corneal ulcer, and that an ulcer only developed if the antibiotic was applied more than 18 hours after the eye trauma. Microbial keratitis is an infection of the cornea. Corneal opacities, which are frequently due to microbial keratitis, remain among the top 5 causes of blindness worldwide. Microbial keratitis disproportionately affects low-and middleincome countries. Studies indicate that the incidence of microbial keratitis may be up to 10 times higher in countries like Nepal and India compared to the United States.
Rural agricultural communities in lowand middle-income countries face a particularly high burden from corneal blindness. The most common cause of microbial keratitis is infection following a corneal abrasion. People are at greater risk of corneal injuries from agricultural activities, manual labour, and domestic work, which can result in infections of the cornea through contact with contaminated objects. Microbial keratitis tends to affect people at younger ages, in their prime working years, compared to other causes of blindness (such as cataract), which generally affect older people Rural communities in low-and middleincome countries face numerous obstacles in accessing appropriate treatment for microbial keratitis. Long delays in presentation and use of traditional medicines are common, increasing the risk of perforation and other complications that may result in vision loss. Patients with corneal ulcers may also face worse outcomes due to a lack of effective treatment options as well as an inability to afford medications when treatment is available. Opportunities for rehabilitation through surgical procedures are also limited by a lack of donor corneas for transplants.
Even when appropriate medical care is available, the corneal scarring that accompanies healing often results in visual impairment, despite successful antimicrobial treatment. Trials comparing antimicrobials for microbial keratitis generally have been unable to discern differences in visual acuity after treatment. An exception is that natamycin has been shown to be more effective than voriconazole for fungal corneal ulcers. Studies trialling adjunctive therapies with agents, such as topical corticosteroids, to reduce scarring, also have been largely unable to demonstrate major differences in visual outcomes in bacterial keratitis.
Given the limitations associated with available treatment options, secondary prevention (i.e. the prevention of visual impairment in someone with a corneal injury and/or infection) may be the best option for reducing vision loss associated with microbial keratitis.
A series of studies in Southeast Asia suggested that antimicrobial ointment applied soon after a corneal abrasion could dramatically reduce the incidence of microbial keratitis. The Bhaktapur Eye Study in Nepal was the first of these to show promising results for microbial keratitis prevention programmes at village level. In this study, primary eye care workers from the community were trained to diagnose corneal abrasions with fluorescein strips and a blue torch. They then provided topical chloramphenicol to all patients with a corneal epithelial defect. This study found that only 4% of patients treated for a corneal abrasion developed a corneal ulcer, and that an ulcer only developed if the antibiotic was applied

Microbial keratitis: a community eye health approach
This issue of the Community Eye Health Journal focuses on micobial keratitiscorneal ulceration caused by microorganisms, which is a major cause of unilateral and some cases of bilateral corneal blindness, particularly in rural low resource settings. The aim of the issue is to promote good practice in preventing, diagnosing and treating microbial keratitis. There are also practical articles on how to take a corneal scrape in microbial keratitis and the indications and procedure for tarshorrhaphy. We hope you find the articles of help in your work and we look forward to receiving any comments you may have. A similar study conducted in Bhutan corroborated the Nepal study's findings, and suggested that a microbial keratitis prevention programme may be effective even in isolated rural areas. In Myanmar, low rates -much lower than previous estimates -of bacterial and fungal ulcers were observed after the institution of the village eye worker programme. In a trial conducted in South India in individuals with corneal abrasions, those randomised to antibiotic prophylaxis had low rates of corneal ulcers, similar to rates observed in patients randomised to antibiotic plus antifungal prophylaxis, suggesting that antibacterial prophylaxis alone might prevent both bacterial and fungal infections. These studies demonstrated that village health workers can be trained to diagnose corneal abrasions and provide prophylactic treatment, and suggested that this simple intervention might be effective.

ABOUT THIS ISSUE
These studies also indicate that the following simple tools may be used to identify and prevent microbial keratitis. As infectious ocular diseases decline, microbial keratitis continues to be a major cause of vision loss globally. While the continued exploration of treatment options for corneal ulcers is essential, we must also focus efforts on opportunities for prevention. In low-and middle-income countries, the prevention of microbial keratitis is a promising intervention for reducing corneal blindness. A large community randomised trial (Village Integrated Eye Worker trial, NIH-NEI U10EY022880) examining corneal ulcer prevention by trained village-level health workers is currently underway in Nepal. Similarly, another study in south India will further examine corneal ulcer education programmes. Looking forward, with increased awareness and implementation of preventive strategies, it should be possible to reduce the burden of corneal blindness worldwide.

Diagnosing and managing microbial keratitis
Infections of the cornea can lead to corneal opacity and blindness if not identified quickly and managed appropriately. The terms 'microbial keratitis', 'infective keratitis' and 'suppurative keratitis' are all used to describe suppurative infections of the cornea. In this issue we use the term microbial keratitis. These infections are characterised by the presence of white or yellowish infiltrates in the corneal stroma, with or without an overlaying corneal epithelial defect, and associated with signs of inflammation ( Figure 1).
The common symptomatic complaints of patients with microbial keratitis are as follows (all with varying degrees of severity): • redness of the eye • pain • blurring of vision • photophobia • watering or discharge from the eye.
The aim of this article is to review both bacterial and fungal keratitis, with an emphasis on identification and management at the primary, secondary, and tertiary levels. Guidelines for referral will be suggested.

Diagnosis
History taking History taking is an important step in the management of corneal infection. If there has been an injury, ask when and where the injury was sustained, what the patient was doing at the time of injury, whether or not he or she sought help following the injury, and what treatmentincluding traditional eye medicationshad been used. A past history of conjunctivitis may suggest that the infection is secondary to a conjunctival pathogen.

Examination
1 Visual acuity Visual acuity should always be recorded in co-operative patients. If it is not possible to record the visual acuity of a child, for example, a note of this should be made. Vision should be recorded first in the unaffected eye, then in the affected eye; with or without glasses. This provides a useful guide to the prognosis and response to treatment. It is also important documentation in the event of medico-legal issues.
2 Examination of the cornea A torch with a good source of focused light and a loupe for magnification are essential. A slit lamp microscope, if available, is always helpful, but not absolutely essential.
Another essential tool is fluorescein dye, either in a sterile strip or a sterile solution.
Fluorescein stains any part of the cornea that has lost the epithelium, even due to a trivial injury, and appears brilliant green when viewed under blue light ( Figure 3).

Clinical signs
When you examine the eye, look for the presence of the following signs and document them carefully in the clinical notes. This will be helpful when considering whether the eye is responding to treatment.
a. Eyelid abnormalities -such as trichiasis and lagophthalmos b. Reduced corneal sensation c. Conjunctival inflammation and discharge d. Corneal epithelial defects (confirmed with fluorescein) -size and shape e. Corneal inflammatory infiltrate -size and shape f. Thinning or perforation of the cornea g. Hypopyon.
Please refer to the article on clinical signs for clues about the likely cause of the infection (page 6).

Microbiology
For lesions >2mm in diameter, a corneal scrape sample should be collected for microbiological analysis whenever possible. Please refer to the article on page 8.

Management at primary level
Microbial keratitis is an ophthalmic emergency, which should be referred to the nearest secondary/district eye centre for proper management. The following are useful guidelines when referring the patient.
• Do apply antibiotic drops or ointment.
• Do instruct patients and/or their accompanying persons to apply drops frequently until patients arrive at the centre. • Do instruct patients and/or their accompanying persons to avoid traditional medicines. • Don't give systemic antibiotics; they are not helpful. • Don't use steroid drops and/or ointment; they can be dangerous. • Don't routinely patch the eye; it is not necessary.     Adjunctive treatment • Atropine 1% or homatropine 2% could be used twice a day to dilate the pupil; this helps to prevent synechiae and relieve pain • Oral analgesics will help to minimise pain • Anti-glaucoma medication may be advisable if the intraocular pressure is high • Vitamin A supplements may be helpful, particularly in countries where vitamin A deficiency is prevalent.

Management at secondary level
Remember the five As: Antibiotic/antifungal, Atropine, Analgesics, Anti-glaucoma medications, and Vitamin A.

Subsequent management
Microbial keratitis patients should be admitted and examined daily (if possible with a slit lamp) so that their response to treatment can be evaluated and the frequency of antibiotics adjusted accordingly. Reduce the frequency of antibiotic administration when the patient experiences symptomatic improvement (less tearing and photophobia, relief from pain and improvement in vision), and when the ulcer shows signs of improvement, including: • decrease in lid oedema • decrease in conjunctival chemosis and bulbar conjunctival injection • reduction in density of the infiltrate and area of epithelial ulceration • reduction of haziness of the perimeter of the ulcer and of the stromal infiltrate • decrease in inflammation, cells, fibrin, and level of hypopyon • dilatation of pupil.
If the patient is judged to be improving, the dose of antibiotics and/or antifungal drops should be reduced from hourly to 2-hourly, then 4-hourly over the next 2 weeks for bacterial ulcers. For fungal ulcers, treatment should be continued with three-hourly drops for at least three weeks, as late reactivation of infection can occur. Longer courses may be needed in more severe cases.
Note: In the case of bacterial infection, the inflammatory reaction may be enhanced by endotoxin release during the first 48 hours of treatment; however, definite progression at this stage is unusual and implies that either the organisms are resistant to therapy, or the patient is not instilling the drops as prescribed. 1 Guidelines for referral to a tertiary centre Immediate referral on presentation if: • the ulcer is in an only eye • the patient is a child • there is impending or actual perforation.
Following initial treatment, if cases of bacterial ulcer fail to show any improvement within 3 days, and fungal ulcers within a week, patients should be referred to a tertiary care centre.

Management of corneal ulcer at tertiary level
Many tertiary eye care centres have their own protocol for the management of corneal ulcer. The management suggested is based on a WHO recommendation with suitable modification according to local circumstances. 2 Background, examination, and recording of findings By the time patients have reached a tertiary centre, they will have travelled from one place to another (with attendant hassles) received several treatments, may have lost faith in eye care personnel, and may already have run out of money, (particularly in low-income countries). Considering this broader personal situation is important in the overall care of corneal ulcer patients.
A careful history of the development of the disease may point to the existence of an underlying predisposing condition such as diabetes mellitus, immunosuppression due to local or systemic steroids (or other immunosuppressants), dacryocystitis, or other ocular conditions. A full list of drugs used by the patient should be obtained to ensure that drugs which have not helped in the past are not repeated; this may also help to discover possible drug allergies. Findings should be carefully noted on a standard form.
A meticulous corneal scraping subjected to laboratory processing often provides a sound guideline to treatment (see page 8).

Hospitalisation
This provides patients with rest and adequate medication; they can also receive frequent follow-up, management of systemic problems, such as diabetes, and further surgical intervention, if warranted.

Treatment
The initial treatment (see Tables 1 and 2) depends on the results of the corneal scrape and the local pattern of pathogens and antibiotic resistance.
• If microscopy is negative, if it is not possible to perform a corneal scrape, if Gram-positive or Gram-negative bacteria are visualised, treat the patient with antibiotic eyedrops. Use either a combination of cefazolin 5% and gentamycin 1.4%, or fluoroquinolone monotherapy (e.g. ciprofloxacin 0.3% or ofloxacin 0.3%).
To begin with, drops should be given hourly for 2 days and then tapered, based on response. • If microscopy reveals fungal hyphae, topical natamycin 5% or amphotericin-B 0.15% should be used hourly for a week and then tapered. • If the ulcer seems to respond well to treatment, continue therapy as before for 2 weeks for a bacterial ulcer and at least 3 weeks for a fungal ulcer.

DIAGNOSIS AND MANAGEMENT Continued
• If the response is poor and the culture shows growth of a bacterial organism, the choice of antibiotic is guided by the sensitivity reports.
Natamycin 5% suspension is recommended for treatment of most cases of filamentous fungal keratitis, particularly those caused by Fusarium sp. Natamycin 5% was found to be more effective than voriconazole in a recent clinical trial.
Most clinical and experimental evidence suggests that topical amphotericin-B (0.15 -0.5%) is the most efficacious agent available to treat yeast keratitis. Amphotericin-B is also effective for fungal keratitis caused by Aspergillus sp.
Oral anti-fungal agents may be considered as an adjunctive therapy in more severe fungal keratitis with deep corneal or intraocular involvement. Oral fluconazole (200-400 mg/day) has been used successfully for severe keratitis caused by yeasts. Oral itraconazole (200 mg/day) has broad-spectrum activity against all Aspergillus sp. and Candida but has variable activity against Fusarium sp. More recently oral voriconazole has been used in cases of keratitis due to filamentary fungus.
Other agents such as polyhexamethylene biguanide (PHMB) 0.02%, chlorhexidine 0.02%, povidone iodine 1.5 -5% and silver sulfadiazine 1% have been reported to possess variable antifungal activity and may be used if other drugs are not available.
Fungal infection of the deep corneal stroma may not respond to topical antifungal therapy because of poor penetration of these agents in the presence of an intact epithelium. It has been reported that a 5 mm epithelial debridement (as a diagnostic scraping or therapeutic procedure) greatly enhances the penetration of antifungal drugs.
Animal experiments indicate that frequent topical application (every five minutes) for an hour can readily achieve therapeutic level.

Surgical management
The range of surgical interventions available for management of corneal ulcers can include debridement, corneal biopsy, tissue adhesives, conjunctival flap, tarsorraphy, or therapeutic corneal graft. Evisceration of the eye is performed for severe pain, panophthalmitis, or lifethreatening complications.

Tarsorrhaphy
This is an old surgical technique that is still very useful today. Tarsorrhaphy often leads to rapid resolution of persistent epithelial defects, whatever the underlying cause. Tarsorrhapy is effective in promoting healing in microbial keratitis caused by fungal and bacterial infections, provided the ulcer has been sterilised by effective antibacterial and/or antifungal treatment. It can be difficult to instil drops and to see the cornea following central tarsorrhaphy, so it is vital to ensure that the infection is under control before closing the eyelids. See page 10 for a description of two useful tarsorrhaphy techniques.

Conjunctival flap
The principle of this technique is to promote healing of a corneal lesion by providing adequate nutrition via the conjunctival blood vessels. The flap could be of three types: Although a large number of antifungal drugs are available for systemic mycoses, only a few are effective for treatment of corneal ulcers. The commonly recommended drugs are listed in Table 2.

Conclusion
Management of microbial keratitis remains a major challenge worldwide, more so in low-and middle-income countries with inadequate health care resources.
Although the outcome of treatment has improved significantly, many patients continue to deteriorate in spite of the best treatment that can be offered. The continued emergence of strains of microorganisms that are resistant to an ever-expanding range of antimicrobials poses an additional challenge. Further research related to prevention of microbial keratitis and enhancing host resistance are two worthwhile goals to pursue. Largescale public education programmes to alert those at risk of microbial keratitis, and to encourage earlier presentation, should be undertaken. Coupled with this, education of practitioners, general physicians, and other health workers, as well as general ophthalmologists, will go a long way towards ensuring correct diagnosis, appropriate treatment and timely referral before extensive damage to the cornea occurs. Several studies have indicated that the best way to prevent corneal ulcers in low-and middle-income countries is to treat corneal abrasions in the primary care setting within 48 hours of the injury. [3][4][5][6] This could be adopted in any population and is cost-effective for both health providers and the patient.  'It is not feasible or desirable to prescribe empirical antifungal therapy to every patient who presents with microbial keratitis in tropical regions, where fungal infections are more frequent.' profile) were independently associated with fungal keratitis, and the anterior chamber fibrin was independently associated with bacterial keratitis. 1 Some of these features are illustrated in Figure 1. By combining information about all three features in an algorithm (Figure 2), it is possible to obtain a probability score for the likelihood that the microbial keratitis case is due to a fungus.
Challenge: Use the algorithm (Figure 2) to estimate the probability that the microbial keratitis case in Figure 3 is due to a fungal infection. The algorithm is primarily for use as a guide in settings where clinicians do not have any laboratory facilities and treatment decisions have to be made based on clinical judgement alone. Where diagnostic microbiology is available it is strongly recommended that it is used. As discussed in the article on laboratory diagnosis in this issue, microscopy alone can provide a diagnosis if an infection is fungal; the presence of fungal hyphae in corneal tissue is a definitive diagnosis.
bacterial keratitis on clinical signs Matthew Burton   This article aims to provide a comprehensive guide to taking a corneal scrape and making a diagnosis (Figures 1-4). However, there are settings in which there are either limited or no laboratory facilities available to the ophthalmologist; for example, at primary level eye care centres in rural locations. In these circumstances, microscopy may still provide valuable information to guide clinicians in their choice of treatment ( Figures 5-11 are images of infected corneal tissue as seen by microscopy).

Taking a corneal scrape
What you will need: • 21-gauge needles or Kimura scalpel • Two clean microscope slides • One fish blood agar plate (FBA) • One Sabouraud glucose agar plate (SGA) • One batch brain heart infusion broth (BHI) (for fastidious organisms) • One batch cooked meat broth (CMB) (excludes facultative anaerobes) • One batch thioglycollate broth (TB) • One batch non-nutrient agar (NNA) (if Acanthamoeba sp. is suspected) In order to have the best possible chance of providing the clinician with an accurate diagnosis, all the media listed are required. In some remote settings, some media may not be available or there may be limitations in the variety of media it is possible to process. For these situations, the minimum requirements are denoted by bold type, in order of importance. Liquid phase media (broths) must be used when available. If only one liquid phase media is to be used, this should be BHI; it is essential to inoculate more than one bottle. NNA is indicated only if amoebic infection is suspected.
General principles • If possible, withdraw the use of antimicrobial agents for 24 hours prior to sampling. Where this is not possible, the use of liquid phase media, for example BHI, serves as a diluent that reduces the concentration of the drug below the minimum inhibitory concentration (MIC). • Apply anaesthetic drops that do not contain preservative. • Use a different needle to take each specimen or, if using a Kimura scalpel, flame the scalpel between samples. • If fungal or amoebic infection is suspected, it is preferable to sample material from the deeper stromal layer of the cornea.
Order of specimen preparation: 1 Slide for Gram stain and slide for alternative staining processes 2 Solid phase media (FBA/HBA, SGA, NNA) 3 Liquid phase media (BHI, CMB, TB) If the ulcer is very discrete, or only a small amount of corneal material is available, inoculate one solid and one liquid phase medium.
Specimen collection for microscopy • Label slide with patient's name, date of birth, and hospital number.
• Draw/etch a circle on the slide and place specimen within the circle (Figure 2). • Air-dry and cover with a protective slide (tape the ends) or place in a slide transport box.
Inoculating culture media • Gently smear material on the surface of agar in C-streaks ( Figure 3); taking care not to puncture the surface of the agar. • Sellotape the lid of the plate to the base around the perimeter. • Incubate inoculated culture media as soon as possible. Refrigeration of specimens is to be discouraged and, if not being transported directly to the laboratory, it is preferable to keep samples at room temperature.

Making a diagnosis
Microscopy: the Gram stain 1 Air-dry and heat-fix specimen using a Bunsen burner or spirit lamp 2 Allow slide to cool on staining rack 3 Flood slide with crystal violet; leave for 1 minute (Figure 4) 4 Rinse slide in clean running water 5 Flood slide with Gram's iodine; leave for 1 minute 6 Rinse slide in clean running water 7 Apply acetone and rinse immediately under running water (exposure to acetone <2 seconds) 8 Counter-stain with carbol fuschin for 30 seconds 9 Rinse in clean running water then dry with blotting paper 10 View specimen with 10x objective 11 Place a drop of immersion oil on the slide and view with 100x oil-immersion objective.
• Gram positive (+ve) cocci most commonly associated with suppurative keratitis are the Staphylococci ( Figure 5) and Streptococci (Figure 6, Streptococcus pneumoniae).    Although the Gram stain is not the first choice of stain for specimens containing fungi, yeast cells, pseudohyphae and fungal hyphae may be observed in Gram-stained corneal material. Apart from yeast cells, which will stain Gram-positive, hyphae and pseudohyphae will stain either negatively or Gram-variable. In order to provide a more definitive diagnosis, prepare a second corneal scrape preparation using a more appropriate stain, e.g. lactophenol blue.
1 Add a drop of lactophenol cotton blue mountant to the slide. 2 Holding the coverslip between your forefinger and thumb, touch one edge of the drop of mountant with the coverslip edge, then lower it gently, avoiding air bubbles. The preparation is now ready. 3 Initial observation should be made using the low power objective (10x), switching to the higher power (40x) objective for a more detailed examination. 4 Calcofluor white and Periodic Acid Schiff reaction (PAS) staining may also be used.

Diagnostic criteria
As applied to bacterial culture: • the same organism growing at the site of inoculation on two or more solid phase cultures, or • growth at site of inoculation on one solid phase media of an organism consistent with microscopy, or • confluent growth on one media.

Amoebic infections
The cyst form of Acanthamoeba sp. can be visualised in corneal material using a direct fluorescent technique such as calcofluor white (Figure 11), haemotoxylin and eosin, LPCB or PAS. If corneal infection with Acanthamoeba sp. is suspected, inoculate corneal material onto non-nutrient agar in a demarcated area of the plate. In the laboratory, the square of agar where the specimen was inoculated will be excised and inverted onto an NNA plate seeded with a lawn of E.coli. Growth of the trophozoite form is imperative to confirm viability of the organism and thus prove it to be the organism responsible for infection ( Figure 12).

What is tarsorrhaphy?
Tarsorrhaphy is the joining of part or all of the upper and lower eyelids so as to partially or completely close the eye. Temporary tarsorrhaphies are used to help the cornea heal or to protect the cornea during a short period of exposure or disease. Permanent tarsorraphies are used to permanently protect the cornea from a long-term risk of damage. A permanent tarsorrhaphy usually only closes the lateral (outer) eyelids, so that the patient can still see through the central opening and the eye can still be examined.

What are the indications for tarsorrhaphy?
To protect the cornea in the case of: • inadequate eyelid closure, for example due to facial nerve palsy or cicatricial (scarring) damage to the eyelids caused by a chemical or burns injury • an anaesthetic (neuropathic) cornea that is at risk of damage and infection • marked protrusion of the eye (proptosis) causing a risk of corneal exposure • poor or infrequent blinking, for example in patients in intensive care or with severe brain injuries.
To promote healing of the cornea in patients with: • an infected corneal ulcer, which is taking a long time to heal • non-healing epithelial abrasions.

Other indications include:
• To prevent conjunctival swelling (chemosis) and exposure after ocular surgery • To retain a conformer or other device, for example in children with anophthalmia or adults after evisceration or enucleation.
What are the different types of tarsorrhaphy?
The techniques for joining part or all of the upper and lower lids can be divided into short-term (temporary) and long-term (permanent) tarsorrhaphies. In both cases the procedure almost always involves using a suture to join the lids.
Other techniques that are occasionally used are botulinum toxin tarsorrhaphy (the upper lid levator muscle is paralysed with the toxin), or the use of cyanoacrylate glue to join the lids and placing a weight (usually gold) in the upper lid.
We will describe two simple procedures: • A temporary central tarsorrhaphy with a drawstring that allows it to be repeatedly opened and closed for examining the eye. • A permanent lateral tarsorrhaphy that leaves the central lids open, allowing the patient to see and the eye to be examined.
The drawstring temporary central tarsorrhaphy (Figures 1a and 1b) This simple suture tarsorrhaphy will be effective for 2-8 weeks.
1 Anaesthetise the central area of both the upper and lower eyelids with an injection of a few millilitres of local anaesthetic (e.g. lidocaine 1-2% or bupivacaine 0.5%). If anaesthetic with adrenaline is available it will reduce operative bleeding. 2 Clean the area with 5% povidone iodine. Leave the iodine for a few minutes. During this time prepare two x 2cm bolsters and one x 1cm bolster. The sutures are tied over the bolster (e.g. plastic tubing or small cotton wool balls) to prevent them cutting into the skin. They can be made from paediatric butterfly cannulas or other similar sterile plastic tubing. Cut each bit of tubing lengthwise to prepare a bolster 'gutter'.
3 Pass a double-armed non-absorbable suture (e.g. silk, prolene or nylon 4-0, 5-0 or 6-0) straight through one of the 2cm bolsters, 2 mm from the end.   The permanent tarsorrhaphy (Figure 2a-f) The upper and lower lids will not stay 'stuck' together when the sutures of a temporary tarsorrhaphy lose their tension after a few weeks. In a permanent tarsorrhaphy, some of the lid margin is debrided which allows the lids to stick together as they heal. Permanent tarsorrhaphies are almost always only lateral so that the patient can still see out of the central eyelid opening and the eye can still be examined. They should last at least 3 months (and sometimes forever).
The steps of a permanent lateral tarsorrhaphy are: 1 Anaesthetise the upper and lower lids as above. When you have finished the procedure note the following two things (Figure 2f): • If you have neatly joined the lateral third of the upper and lower eyelids, there will still be an opening that the patient can see through. The opening will obviously be narrower horizontally, but it will also be narrower vertically, which will give more protection to the cornea in the open area. • In this procedure, the anterior lamella and eyelashes are undamagedtherefore if the tarsorrhaphy is opened at a later date, the lid will look almost normal. These tarsorrhaphies often last forever, but if they need to be divided this can be done by injecting some local anaesthetic and cutting the sutures. Measuring the outcome of cataract surgery: the importance of the patient perspective Most eye care staff have had the pleasure of removing the pad from a patient's eye after cataract surgery and seeing their joy at having their sight restored. However, when the outcome of cataract surgery is discussed prior to surgery, the first thing most people think about is visual acuity or complications. Whilst these are critically important, they are only part of the story. Imagine the following scenario. An 85-year-old woman presents with a visual acuity of 'hand movements' and dense white cataract in both eyes. She is advised to have cataract surgery. Cataract surgery in the first eye goes well with excellent technical success (a perfect capsulorrhexis, good centration of the intraocular lens, etc.) and her visual acuity improves to 1/60 in her operated eye.
Is this a good outcome? From a technical point of view it is -the surgery went well. However, from a visual acuity perspective, it is not ideal as the woman continues to have poor vision in the operated eye. What we don't know, is what the woman thought about the outcome. Was she happy? If not, why not?

What do patients think?
We can, of course, ask patients about whether they are happy with the outcome of surgery, but we have to remember that -as humans -we are influenced by a variety of different things when considering whether we're happy with any outcome. For example, if the surgeon had told the patient that she would have perfect vision restored by surgery, would she be happy? If she had spent her life savings on surgery, would she be happy?
Understanding the patient's perspective on the visual outcome of cataract surgery can improve our cataract surgical service. It allows the hospital team to identify where improvement is required. For example, if the patient reported that the surgeon told her to expect perfect vision, then the information routinely provided by the surgeon could be reviewed and expectations better managed.
NOTE: Remember to manage the patient's expectations. What you say will depend upon any risk factors and the presence of any co-pathology that might affect the outcome.
So, how can we collect the patient's perspective on outcome? There are several ways: 1 Comments boxes. Many hospitals have comments boxes: patients are encouraged to write down their comments and put them in a box. The advantage of this system is that it is anonymous, so patients can be honest about their care; however, they are of limited use in countries where literacy levels are low. They also rely on ready access to paper and pen, and are less likely to be used by older patients. 2 A questionnaire. Questionnaires are available that capture patients' perspective on the outcome of their care. They either can be given to patients to complete (if they are able), or administered by a member of staff or volunteer. Questionnaires must be culturally appropriate and in the correct language. They rely on either the patient or carer being able to read, or one of the staff helping the patient to complete the questionnaire (which can be problematic as patients might be reluctant to raise concerns or offer criticism in the presence of a staff member).

Patient interviews/exit interviews.
This involves talking with patients about their experiences at the hospital and recording their responses. Ideally, volunteers (or anyone who is not associated with the clinical care patients receive) should ask the questions, in order to ensure that patients feel it is safe to be honest.

What questions to ask
The purpose of getting the patients' perspective is to find out whether he or she is satisfied with our cataract service (and will recommend it to others), and to find out how we can do better. A simple yes/no answer (e.g.: 'Yes, I am satisfied', or 'No, I am not satisfied') is not enough. For example, patients might not have been satisfied because the bed was uncomfortable or because they were expecting their visual acuity to be perfect; these are two very different things requiring different remedial actions. In addition, satisfaction levels may be artificially high as patients might not want to be critical about aspects of their care.
It is usually more helpful to understand patients' experience of the cataract service. Patient experience questionnaires use quantifiable, objective measures of outcome and patient care in order to explore patients' views. A patient experience questionnaire asks a series of questions designed to try and understand the whole picture. For example, questions about: • Information and education provided • physical comfort • emotional support • respect for the patient (e.g. 'Did the doctors/nurses sometimes talk as if you weren't there?') • involvement of family and friends • continuity and transition (e.g. 'Were you shown how to instil eyedrops before you left the hospital?').
It is possible to find free examples of patient experience questionnaires online. 1 These may provide a useful starting point.  Allen Foster, ICEH Co-director

Demonstrating impact
If we want to show that surgery has changed someone's life, then just showing that their vision has improved is not enough. We need to show that they can do things that they could not do before surgery, or that they feel better.
To do this, we can do a 'quality of life' audit. This involves using a specially designed questionnaire and asking a randomly selected group of patients (e.g. every fifth patient) to complete it (with or without help) both before and after surgery. This makes it possible to identify any changes that have occurred and to determine the impact that surgery is having on the lives of patients.
Quality of life questionnaires have been validated (proven) to measure change in a number of areas, including people's ability to function. They ask questions such as: 'Can you read a newspaper?' or: 'Can you recognise faces?'.
Quality of life questionnaires are an objective and independent method of measuring the patient's perspective on outcome. The advantage of using quality of life questionnaires is that, because we are asking for descriptions of what people can and cannot do -rather than how they feel about the outcome -there is less chance that the patient's response will be affected if the interviewer is a staff member.
Many different studies have shown that cataract surgery can improve function, and there are several questionnaires that can be used to assess this. Care has to be taken when using the questionnaires as they are context-specific. This means that each questionnaire has been developed based on the culture of the people that are being questioned. A good example is activities of daily living. In the UK, most people have a television and questionnaires often include a question on the patient's ability to watch programmes before and after surgery. Obviously this is a pointless question in places where there are few televisions. There are also difficulties in translating the questions as many languages use different types of words to describe the same thing. Therefore, care must be taken in choosing a questionnaire that is right for your country, culture and language.
At the hospital we can use quality of life questionnaires to show our patients, our staff and our supporters (including donors) that, not only do most patients see better after surgery, but most have an improved quality of life too. Health, including visual health, is inextricably linked to school achievement, quality of life, and economic productivity. 1 Introducing health education in schools is essential as knowledge and good habits acquired at an early age are likely to persist. Globally, 19 million children are living with vision impairment 2 and approximately 12 million children have a significant, uncorrected refractive error. Of particular concern is the rapid increase in myopia, particularly in East Asia, where 78% of children in China are affected. 3 School eye health programmes, when integrated into broader school health education and backed up by eye and child health services, can reach a large number of children and their families.
School eye health can encompass the following: • Health promotion and prevention to increase awareness among children and teachers and to promote a healthy school environment. This can reduce the impact of local endemic eye diseases such as trachoma. • Primary eye care to detect and treat common eye conditions (e.g. infections), refer people with conditions such as cataract, and to manage refractive errors with high quality, appealing and affordable spectacles.
Activities may include: • Training children to spread eye health messages and conduct simple vision screening among peers and family members (the child-to-child approach). • Showing children and adults how to help and interact with those who are blind or have irreversible low vision.
Children should be offered general vision screening when they enter and leave primary school, and when they leave secondary school/high school. Any child with visible eye conditions (squint, white pupil, red eyes) and associated symptoms (abnormal head/face turn, inability to copy from the blackboard, complaints of chronic headaches), should also be screened and provided with, or referred to, the appropriate services.
The ideal is to conduct eye health screening for children and teachers in school, and refer those who need further management to the eye unit for examination, refraction and dispensing of spectacles. Another option is to screen and refract the children in the school and allow them to choose a frame they like. The local eye unit can cut lenses, fit them and deliver the spectacles to the school.
Factors that contribute to a successful school eye health programme include: • The support and engagement of the local education authorities. • The involvement of parents/carers. • The enforcement of policies and guidelines to prevent unnecessary prescribing (see below). • Financial support for optical correction from the government (child health services/insurance schemes). • Qualified personnel to fit affordable and good quality spectacles.
Spectacles should not be prescribed to children with minimal refractive error. Children will not notice a significant improvement in their vision and will therefore simply not wear them! This is a waste of resources.
The guidelines for correction are: To increase follow-up and referral, the following must be systematically recorded.
• Uptake of referrals (to ensure services are accessed, including low vision care). • Spectacle wearing after 3-4 months and any reasons for non-wear. • Any educational adjustments made for children identified with irreversible vision impairment (by consulting with teachers). • New and/or progressed myopia cases and replacement of broken/missing spectacles (by repeating screening of 11-15 year-old children).
In order to increase coverage, members of school health programmes can work with school nurses and teachers after consultation with educational authorities. In order to make informed decisions, research (which can be multi-disciplinary) plays a pivotal role in providing evidence, which might be needed for: • Planning -needs assessment based on prevalence data, reviews of existing resources and analysis of policy. • Improving implementation -operational research to identify gaps and challenges could improve the efficiency, effectiveness and quality of programmes. • Assessing impact -in terms of satisfaction, academic achievement, quality of life, etc.
Eye health is an essential part of a school health programme and should be comprehensive and respond to the locally relevant eye conditions and diseases. Correction of refractive errors is critical but should not be the only focus of a school eye health programme. Figure 1 describes a systematic approach to school eye health. consists of a generator and a handpiece with one or more electrodes. The device is controlled using a switch on the handpiece or a foot switch. Electrosurgical generators can produce a variety of electrical waveforms. As these waveforms change, so do the corresponding tissue effects.
In bipolar electrosurgery (Figure 1), both the active electrode and return electrode functions are performed at the site of surgery. The two tips of the forceps perform the active and return electrode functions. Only the tissue grasped in the forceps is included in the electrical circuit. Because the return function is performed by one tip of the forceps, no patient return electrode is needed. Bipolar electrosurgery operates regardless of the medium in which it is used, permitting coagulation in a fluid environment -a great advantage when attempting to coagulate in a wet field. As a result, bipolar electrosurgery is often referred to as 'wet field' cautery.
In monopolar electrosurgery (Figure 2), the active electrode is placed at the surgical site. The patient return electrode (also known as a 'dispersive  Electrosurgical generator Patient return electrode Handpiece Active electrode pad' is placed somewhere else on the patient's body. The current passes through the patient as it completes the circuit from the active electrode to the patient return electrode. The function of the patient return electrode is to remove current from the patient safely. A return electrode burn will occur if the heat produced, over time, is not safely dissipated by the size or conductivity of the patient return electrode.
Modern electrosurgical machines have built-in safety features to prevent burns from occurring due to poor contact between the patient and the return electrode when using the monopolar mode.
Often, the term 'electrocautery' is incorrectly used to describe electrosurgery. Electrocautery refers to direct current (electrons flowing in one direction) whereas electrosurgery uses alternating current. In electrosurgery, the patient is included in the circuit and current enters the patient's body. During electrocautery, current does not enter the patient's body. Instead, current flows through a heating element, which burns the tissue by direct transfer of heat. Electrocautery or, more precisely, thermocautery units ( Figure 3) are usually portable battery powered devices that can be either disposable or reusable.

Using the ESU safely
ESUs produce very high current that can injure both patient and operator if not properly used and maintained. Many problems have been associated with the use of ESUs, such as burns at the return electrode site and surgical fires. Some of these safety problems can be avoided by taking simple precautions.

Dos
• The hand piece should always be placed in the nonconductive holster when not in use. • Always use the lowest possible generator setting that will achieve the desired surgical effect. When higher than necessary voltages are used, the chances of arcing are increased. If the surgeon continues to ask for a higher setting, this could be a signal that the integrity of the skin/dispersive pad interface is compromised. • Clean the electrode tip frequently. As eschar (dead tissue from burning) builds up on the tip, electrical impedance increases and this can cause arcing, sparking or ignition and flaming of the eschar. When cleaning the electrode, the eschar should be wiped away using a sponge rather than the common scratch pad, because these pads will scratch grooves into the electrode tip, increasing eschar build-up. Cleaning and dressing the wound • Make sure that you have selected the correct dressing type and materials to provide full and appropriate coverage of the type, size and location of the wound as per the care plan or the physician or senior charge nurse's recommendations.
• Wash your hands and put on sterile gloves. If the gloves become desterilised, remove them, re-wash your hands and put on new sterile gloves. This is best practice, but where resources are not available, safe modifications to this process can be made, for example by using non-sterile gloves to protect the nurse while removing the dressing and then washing the hands with gloves on and using alcohol gel on the gloves to make them clean enough to clean the wound and redo the dressing. This then protects both the nurse and the patient.  In order for MDA to be effective in stopping transmission of ocular Chlamydia, as many as possible of those with current infections should receive the correct dose of Zithromax ® during the distribution. The term 'treatment coverage' is used to describe the proportion of people who received Zithromax® among all those targeted by the MDA. Untreated persons left harbouring an infection are a potential sources of contagion and could be responsible for a fresh outbreak of infection and on-going transmission. Almost all infections are in children and therefore children are the most important targets for Zithromax® treatment.
In a simplified example, if 20% of children (1 in 5) are infected, and all of them receive treatment, none will remain infected and transmission will only be possible by reintroduction from a neighbouring untreated area. But what if not all the infected children are treated? Transmission will likely start again in that district a few months after the distribution.
In our hypothetical district where one in five children are affected, a distribution reaching half of the children (50% coverage) will leave one in 10 children able to transmit ocular Chlamydia. Reaching almost all children (95% coverage) will leave just one in 100 as a potential source of infection. In MDA for trachoma control, coverage matters, and the higher the prevalence of infection, the more important it is to achieve high coverage.
Country programmes routinely report treatment coverage by subtracting the number of doses of Zithromax® left in stock after a distribution from the target population, or by summing the reports from the drug distributors. While both of these methods are better than doing nothing, it is important to check the accuracy of such routinely reported coverage figures, as they are subject to manipulation and error. An effective approach is to conduct a coverage survey. Coverage surveys are investigations in random sample of members of the target population designed to establish the proportion of people who received treatment.
Experience has shown that during MDA, a whole family, village or even group of villages is often missed, meaning that those people do not have the opportunity of treatment with Zithromax ® . Because coverage can be patchy, it is best to survey a large number of villages, but (unlike a prevalence survey) only a few households in each village need to be interviewed. One inexpensive approach to estimate coverage is based on a survey of seven households in each of 30 villages, called the '7x30 method'. The survey team should select 30 villages from the district (or other target population) of interest at random and follow up with at least seven randomly selected households in each, asking the family members if they took Zithromax ® . To help people remember, and to avoid confusion with MDAs for other diseases, it is best to do the survey within a few weeks of the distribution and to show them what the tablets and suspension look like -Zithromax ® is the only MDA that uses pink tablets or a liquid suspension for younger children. Experience suggests it is easy to remember.
Coverage surveys can be used for more than just estimating the proportion of people who received treatment; they can be used to determine why treatment was not taken, allowing for immediate or longer-term remedial action if needed. For example, if a group of villages did not get MDA because no distributor collected Zithromax ® from the health centre, the programme can conduct an immediate 'catch-up' distribution. If coverage was low because people did not wish to participate at the time a long-term process of sensitisation and health education can be planned to improve compliance the following year. Coverage surveys also offer a valuable platform for research, and other important questions regarding the health knowledge, attitudes and practices of the population can be included. It is a sad fact that, despite the technological revolution in eye surgery, there are still 39 million people in the world who are blind, with over half afflicted by cataract.
There is a need for more trained eye staff to carry out high-quality and cost-effective surgery in the hardest-to-reach places. The fourth edition of this classic text is an invaluable aid to anyone wanting to know how to tackle cataract, glaucoma and lid surgery. Just as important, however, is the chain of successful surgery -sterilisation, pre-op preparation, local anaesthesia, magnification and illumination, good instruments, surgical knowledge and technique -all of which are described in detail in the book.
The fourth edition has an expanded section on the principles of learning surgical skills from the novice stage to the competent eye surgeon. The instructions are comprehensive and the line drawings clear. Together with the DVD on suturing, local anaesthesia and operative procedures, and two quizzes, the student will have everything bar the patient! Readers may be surprised to read in detail about intra-capsular cataract extraction with forceps or cryo and retrobulbar anaesthesia, but the long list of potential complications associated with the latter should convince the wise surgeon to use the safer sub-Tenon's instead. Phacoemulsification is quite rightly put on the back burner whilst small incision cataract surgery is given the attention it deserves.
It is a pity that there are a number of typographical errors. Hopefully these will not appear in the fifth edition that will inevitably follow in years to come.